Figure 8.

Counting boxes for neuron density and neuron soma size estimates. As outlined in the Materials and Methods section, and as illustrated here in a section from Aotus trivirgatus temporal isocortex, sampling axes (dashed line) were placed normal to the cortex's outer surface at chosen sites in cortical sections. Along each sampling axis, counting boxes measuring 41 μm × 41 μm (red squares, drawn to scale) were placed, typically at 100 μm intervals, from the surface to the white matter. Neuron density estimates were made within each counting box. In those counting boxes that lay in cortical layers II and III (indicated by the bracket), estimates of neuron soma size were also made.